class / function question

class square{public:	enum square_flag	{		// bit 1-4 store the number of adjacencies		mask		= 0x0F, // 1st - 4th bits are a bit mask to access the count		bomb		= 0x10, // 5th bit is the bomb switch		mark		= 0x20, // 6th bit is used for the mark		visible		= 0x40, // 7th bit is the visiblity		reserved	= 0x80  // 8th bit is unused	};public:	square()	{		m_uiFlags = NULL;	}public:	// set a bit to the flags	void SetFlag(square_flag flag)	{		m_uiFlags |= flag;	}public:	// clear a bit from the flags	void ClearFlag(square_flag flag)	{		m_uiFlags &= ~flag;	}public:	// check whether a flag is set	bool IsFlag(square_flag flag) const	{		return (m_uiFlags & flag) == flag;	}public:	void SetCount(unsigned uiCount)	{		// store the count in 4 reserved bits		m_uiFlags &= ~0x0F;		m_uiFlags |= uiCount & mask;	}public:	unsigned GetCount() const	{		// get the count from the 4 reserved bits		return m_uiFlags & mask;	}protected:	// saves the number of surrounding bombs 	// and flags in one unsigned using bitmasks	unsigned m_uiFlags;};

class board{public:	board(unsigned uiWidth, unsigned uiHeight)	{		// save the width and height		m_uiWidth = uiWidth;		m_uiHeight = uiHeight;		// allocate an array of square arrays		m_ppField = new square*[m_uiWidth];		// for each line of squares		for(unsigned x = 0; x < m_uiWidth; x++)			// allocate an array of squares			m_ppField[x] = new square[m_uiHeight];	}public:	~board()	{		// for each line of squares		for(unsigned x = 0; x < m_uiWidth; x++)			// delete the array of squares			delete[] m_ppField[x];		// delete the array of square arrays		delete[] m_ppField;	}public:	bool FillBySeed(unsigned uiSeed)	{		// set the random seed		srand(uiSeed);		// initialize each square		for(unsigned x = 0; x < m_uiWidth; x++)		for(unsigned y = 0; y < m_uiHeight; y++)		{			// fill the field with bombs			if(rand()%8 == 0)				// random occurance, set the bomb				m_ppField[x][y].SetFlag(square::bomb);		}		// update each square		for(unsigned x = 0; x < m_uiWidth; x++)		for(unsigned y = 0; y < m_uiHeight; y++)		{			// start with a clean count			unsigned uiCount = 0;			// check for bounds			if(x > 0 && y > 0)				// check if it is a bomb				if(m_ppField[x - 1][y - 1].IsFlag(square::bomb))					uiCount++;							// check for bounds			if(y > 0)				// check if it is a bomb				if(m_ppField[x][y - 1].IsFlag(square::bomb))					uiCount++;			// insert the other checks before the update			m_ppField[x][y].SetCount(uiCount);		}		return true;	}public:	bool RenderExample()	{		// render each square		for(unsigned x = 0; x < m_uiWidth; x++)		for(unsigned y = 0; y < m_uiHeight; y++)		{			// save a pointer for simple access			square* s = &m_ppField[x][y];			if(s->IsFlag(square::visible))			{				if(s->IsFlag(square::bomb))					// it is a bomb					DrawBomb();				else					// it is a number					DrawNumber(s->GetCount());			} else			{				if(s->IsFlag(square::mark))					// it is a mark					DrawMark();				else					// it is blank					DrawBlank();			}		}		return true;	}protected:	square** m_ppField;protected:	unsigned m_uiWidth;	unsigned m_uiHeight;};

m_uiFlags &= ~0x0F;m_uiFlags |= uiCount & mask;

// This is of course a very rough sketch with lots of missing thingsclass World {  typedef boost::multi_array<square, 2> grid_t;  grid_t grid;  World(int x, int y): grid(boost::extents[x][y]);  int neighbouringBombs(int x, int y) {    int count = 0;    for (int i = x - 1; i < x + 2; ++i) {      for (int j = y - 1; j < y + 2; ++j) {        // make sure we're in bounds        if (i >= 0 && i < grid.shape()[0] && j >= 0 && j < grid.shape()[1]) {          if (grid[j].hasBomb) {            count++;          }        }      }    }    return count;  }  int appearanceOf(int x, int y) {    switch (grid[x][y].state) {      case HIDDEN:      return HIDDEN_APPEARANCE;      case FLAGGED:      return FLAGGED_APPEARANCE;      case VISIBLE:      if (grid[x][y].hasBomb) {        return EXPLODED_APPEARANCE;      } else {        return VISIBLE_APPEARANCE + neighbouringBombs(x, y);        // we use VISIBLE_APPEARANCE to represent an open square,        // VISIBLE_APPEARANCE + 1 corresponds to the image of a square with a        // '1' on it, etc.      }    }  }  void draw() {    for (int i = 0; i < grid.shape()[0]; ++i) {      for (int j = 0; j < grid.shape()[1]; ++j) {        drawSquareAt(appearanceOf(i, j),                      gridXOffset + i * TILE_SIZE,                      gridYOffset + j * TILE_SIZE);      }    }  }};